1. Field of the Invention
The present invention relates to a showcase for storing foods, etc. under the state that the foods, etc. are kept fresh for a long term to sell the foods, etc. in a store.
2. Description of the Related Art
In a supermarket or a convenience store is placed a showcase which is opened at the front side thereof so that purchasers can easily pick up foods, etc. to be sold (for example, dressed meat, fresh fish, frozen foods, ice cream, etc.). A cooler is provided in such a showcase, and there is known a so-called fin-and-tube type cooler in which plural fins are arranged in alignment with one another so as to be spaced from one another at predetermined intervals, and refrigerant pipes (for example, so-called hair pins or the like may be used) penetrate through through-holes formed in the plural fins. In the cooler, air in the neighborhood of the fins is cooled by the endothermic action of refrigerant flowing in the refrigerant pipes formed by the hair pins, and the cooled air is fed into a storage room in which foods, etc. are displayed, whereby the foods, etc. can be frozen or cooled (for example, see JP-A-11-94442).
In the case of an open showcase which is opened at the front side thereof as described above, outside air freely enters the storage room. Therefore, water components contained in the outside air are cooled by the fins, so that the fins are frosted in some cases. Particularly when the gap between the neighboring fins is small, the gap portion is supercooled and thus the fins are liable to be frosted. In order to prevent the fins from being frosted, the gap between the neighboring fins is kept to a predetermined length or more. These gaps can be secured as follows. That is, the edge portions of the through-holes of the fins are projected by the burring method so that the projecting portions 36 have a predetermined length or more, and the fins are assembled while the projecting portions abut against the adjacent fins, whereby the gaps can be secured.
Furthermore, CO2 refrigerant is used as one of a series of countermeasures to global environment and global warming problems. CO2 refrigerant is used while pressurized till pressure in the neighborhood of the critical point, and the pressure loss is little. Therefore, a refrigerant circuit can be constructed by using a refrigerant pipe narrower (smaller in pipe diameter) than a conventional refrigerant pipe (conversely, a refrigerant pipe having a large diameter needs a larger refrigerant amount and thus the efficiency is lowered).
However, when the refrigerant pipe for CO2 is narrowed, the diameter of the through-holes of the fins is also reduced. Therefore, it is difficult to set the projection length of the projecting portions formed by the burring method to a predetermined length or more. Therefore, in the assembling work of the cooler for CO2 refrigerant, the projecting portions are not used, but a jig for keeping the predetermined length between the fins is separately used.
Furthermore, the hair pin is constructed by bending a refrigerant pipe in an U-shape, and has straight pipe portions which extend in parallel to each other so as to be spaced from each other at a predetermined interval (pitch), and the straight pipe portions penetrate through the plural fins. Plural hole portions are formed in the plural fins, and the straight portions of the hair pins are inserted through the hole portions. For example, there is know a cooler in which plural holes are arranged on three columns along the flow direction of air to be cooled although the number of the columns is varied in accordance with the size, shape, etc. of the cooler. Furthermore, the pitch of the adjacent hole portions is equal to the same dimension of the pitch of the straight pipe portions.
As described above, in the case of the open showcase which is opened at the front side thereof, outside air freely enters the storage room, and the water components contained in the outside air are brought into the fins or the hair pins and cooled, so that the fins or the hair pins are frosted in some cases. Particularly when the straight portions of the plural hair pins are locally densely arranged, the gap between these portions is small and thus air passing through the gap portions is supercooled, and thus the fins and the hair pins are liable to be frosted.
As described above, in order to arrange the hair pins so that the straight portions of the hair pins are not locally dense, it is preferable that the hair pins are not secured so as to be arranged on the same line, but secured so as to be suspended between adjacent columns out of the three columns on which the plural hole portions are arranged. However, when the hair pins are secured to the hole portions of the three columns, with respect to only one line, it is difficult to suspend the hair pins between this line and another adjacent line, and the hair pins must be arranged on only this one line. Therefore, the straight portions are densely arranged in the neighborhood of the hair pins arranged on the same line. Accordingly, the flow of air to be cooled may be disturbed by frost occurring at these portions.